The present invention relates generally to syringes and more particularly to hypodermic syringes.
Syringes are commonly used, for example in the fields of medicine and dentistry, to deliver controlled quantities of fluids, typically liquids, to desired locations. One common type of syringe used in both medicine and dentistry is the hypodermic syringe. Hypodermic syringes are designed for the subcutaneous administration of fluids to a patient in need thereof and typically comprise an elongated body, a plunger and a hypodermic needle. In one well-known type of hypodermic syringe, the elongated body is substantially hollow and the plunger is slidably mounted within the elongated body from one end thereof, the elongated body and the plunger together defining a fluid-tight reservoir. The hypodermic needle is mounted on the end of the elongated body opposite the plunger, the hypodermic needle being in fluid communication with the reservoir through a small orifice formed in the elongated body. Typically, to load the above-described hypodermic syringe with a desired liquid, the hypodermic needle is inserted into a supply of the desired liquid while the plunger is in a depressed position; the plunger is then pulled outwardly, thereby drawing the liquid into the reservoir through the hypodermic needle. Thereafter, to dispense the fluid from the syringe into a patient's tissue, the hypodermic needle is inserted into the tissue and the plunger is depressed.
Another well-known type of hypodermic syringe is shown in FIGS. 1 and 2 herein and is represented generally by reference numeral 11. Syringe 11 is specifically designed for dispensing fluid from a certain type of fluid container referred to in the art as a "carpule." An example of a carpule is illustratively shown in FIG. 3 and represented generally therein by reference numeral 3, carpule 3 comprising a cylindrically-shaped tube 5 having one end sealed with a slidably mounted plug 7 and the other end sealed with a puncturable cap 9.
Referring back now to FIGS. 1 and 2, syringe 11 can be seen to include a body 13. Body 13, in turn, includes a hollow, generally cylindrical member 19 and an hourglass shaped base member (or handle) 21, cylindrical member 19 being partially inserted into and fixedly secured within a longitudinally extending bore 31 formed in base member 21.
Member 19, which is shaped to define a chamber 20 adapted to removably receive a carpule, has an internally-treaded open top end 27 and an open bottom end 29. An externally-threaded boss 30 provided with a longitudinal bore 32 is partially inserted into top end 27 of member 19 and removably mounted therewithin. A large oval-shaped opening 23 is provided on one side of member 19 through which a carpule may be inserted into or removed from chamber 20. A small oval-shaped opening 25 is provided on member 19 opposite opening 23 to permit access to chamber 20 so as to facilitate the removal of a carpule from chamber 20 through opening 23.
A small opening 33 is provided in the bottom end of member 21 to permit access to bore 31, bore 31 extending from the top of base member 21 to just above the bottom thereof.
Syringe 11 also includes a platform 35 of annular shape which is slidably mounted within that portion of member 19 that is disposed within bore 31. (Further upward movement of platform 35 into that portion of member 19 not disposed within bore 31 is prevented by a slight narrowing in the cross-sectional diameter of member 19.) Platform 35 is used to support the bottom of a carpule disposed within chamber 20. Platform 35 itself rests upon a spring 37 also disposed within that portion of member 19 located within bore 31. To facilitate the insertion and removal of a carpule into chamber 20, platform 35 may be lowered within member 19 by pushing platform 35 downwardly against spring 37, thereby compressing spring 37.
Syringe 11 also includes a plunger 41. Plunger 41 comprises an elongated stem 43 which extends upwardly through opening 33 of member 21 and is adapted for slidable axial movement within member 19. The top end of stem 43 is shaped to include a flange 44 which is adapted to engage an inner lip 36 formed on platform 35 for use in pushing platform 35 downwardly against spring 37. Plunger 41 also comprises a harpoon 45 fixedly mounted on the top of flange 44. Harpoon 45 is used to engage the slidably mounted plug of a carpule loaded in chamber 20. Plunger 41 further comprises a ring 47, which is fixedly mounted on the bottom end of stem 43. Ring 47 is adapted to receive the thumb or finger of a user for use in sliding stem 43 axially within member 19.
Syringe 11 further includes a hypodermic needle assembly 51. Needle assembly 51 includes a base 53 and a hypodermic needle 55. Base 53 is internally-threaded so as to be threadingly mounted on boss 30. Hypodermic needle 55 is fixedly mounted in base 53, with its lower end extending down through base 53 into chamber 20 so as to puncture the puncturable cap of a carpule present within chamber 20 and so as to receive fluid from the carpule when plunger 41 is depressed.
To use syringe 11 to dispense liquid from a carpule, one first loads the desired carpule into syringe 11. This loading step may be done by pulling down on ring 47 of plunger 41 so as to lower platform 35 within member 19 while, at the same time, inserting the lower end of the carpule into chamber 20 through opening 23. When platform 35 is sufficiently lowered, the entire carpule is capable of fitting into place within chamber 20. Plunger 41 is then released, causing platform 35 to return back to its normal position and causing the top cap of the carpule to be punctured by the bottom end of needle 55. To dispense the liquid contained within the carpule through needle 55, one presses plunger 41 upwardly. This causes harpoon 45 to engage the slidably mounted plug in the carpule and push it upwardly, thereby forcing the contents of the carpule out through needle 55.
One application of hypodermic syringe 11 in dentistry is in the administration of anesthetic liquids, such as LIDOCAINE, to dental tissues prior to certain dental procedures. Typically, such anesthetic liquids are packaged in standard-sized carpules containing about 1.8 ml of fluid. Unfortunately, such a quantity of anesthetic fluid is typically insufficient to appropriately anesthetize a patient. Accordingly, to administer the necessary quantity of anesthetic fluid to a patient, a dental care provider frequently must repeat, as necessary, the steps of loading a single carpule into the hypodermic syringe and then dispensing the contents of the carpule into the patient's dental tissue. As can readily be appreciated, it can be quite cumbersome for the dental care provider to have to repeat the steps of loading a single carpule and then dispensing its contents for a multiplicity of carpules. Moreover, the foregoing routine also requires that, for each carpule used, the dental care provider must "stick" the patient with the hypodermic needle (and, thereafter, aspirate to ensure that the needle has not hit a blood vessel).
Accordingly, the present inventor has identified a need for a hypodermic syringe which is capable of holding a plurality of anesthetic fluid carpules at one time and which is capable of dispensing the contents of said plurality of carpules without requiring multiple needle sticks (assuming that the needle has not hit a blood vessel).
In U.S. Pat No. 3,767,085, inventors Cannon et al., which issued Oct. 23, 1973, and which is herein incorporated by reference, there is disclosed a double barrel carpule type syringe having, at its discharge end, a common mixing and dispensing chamber provided with a rotary agitator driven from a motor on the syringe. One barrel of the carpule contains an elastomeric base material and the other an accelerator therefor. The syringe has a double plunger by means of which the base material and the accelerator are simultaneously discharged into the chamber in prescribed proportions as the mixed material is discharged from the end of the chamber. The mixing chamber assembly and the carpule assembly are readily removable from the body of the syringe.
In U.S. Pat No. 4,367,737, inventors Kozam et al., which issued Jan. 11, 1983, and which is herein incorporated by reference, there is disclosed a multiple barrel syringe for selective delivery of two different types of fluids. The syringe comprises a body having a pair of bores each containing a plunger and each terminating in a smaller sized conduit for receiving fluid from the bores. Connected to the body is a movable member having a single conduit or passage and a needle mounted on the member and communicating with the bore. The movable member may be manually actuated to bring its single conduit into communication with a selected bore conduit for providing passage of fluid from the selected bore to the needle. The movable member may then be moved to another position to bring the needle into communication with the other bore. Sealing means are provided on the movable member to avoid leakage and feedback of fluid from or to the bore not dispensing fluid.
In U.S. Pat. No. 4,874,368, inventors Miller et al., which issued Oct. 17, 1989, and which is herein incorporated by reference, there is disclosed an improved fibrin glue delivery system. The delivery system comprises a pair of syringe tubes, which can be actuated by plungers simultaneously or independently, a connecting member which holds the syringe tubes in parallel alignment and a unique needle assembly which ensures the components in the syringe bodies will not be commingled until they reach the treatment site. The unique needle assembly also permits the user to manipulate the needles to enhance visibility when the surgeon is working through a speculum or when direct access is difficult. One of the syringe tubes contains fibrinogen and the other syringe tube contains thrombin.
In U.S. Pat. No. 5,290,259, inventor Fischer, which issued Mar. 1, 1994, and which is herein incorporated by reference, there is disclosed a double syringe delivery system for holding a pair of syringes in a manner so as to accommodate the simultaneous activation of the plunger of each syringe in order to effect simultaneous delivery of the contents of each syringe, each syringe containing different contents. The double syringe delivery system includes an elongated support member that is placed between the barrel of each syringe. The elongated support member has resilient, C-shaped clamps on opposite sides of the support member. The clamps are used for holding the syringe barrels of both syringes so that the syringe barrels will be held together in a parallel manner. Further, elongated support member and clamps hold the syringe barrels in a fashion that is slightly longitudinally offset from one another to permit the two syringe barrels to be held together as closely as possible. An interconnecting bridge member connects the two syringe plungers so that they can also be simultaneously activated even though they are also slightly longitudinally offset from one another.
In U.S. Pat. No. 5,354,284, inventors Haber et al., which issued Oct. 11, 1994, and which is herein incorporated by reference, there is disclosed a multiple injection syringe system having a cartridge carrier that is loaded with three pre-filled cartridges which are to be selectively accessed so that the contents of the cartridges can be delivered to a patient in a particular, predetermined order. The syringe system of the present invention has particular application to facilitating the SASH process, such that two of the cartridges are filled with saline and one with heparin. A double ended needle cannula is carried by a rotatable manifold. One end of the cannula projects outwardly from the manifold for administering an injection, while the opposite end projects inwardly to communicate with a selected cartridge within the carrier. The manifold is rotated around the cartridge carrier to each of three positions corresponding to three steps of the SASH process, whereby the cannula is correspondingly rotated from one cartridge to the next. Fluid from the selected cartridge is expulsed via the cannula by applying to said cartridge a hydraulic pressure that is generated by driving a piston through a fluid filled cylinder.